Elastocaloric cooling using shape memory alloys (SMAs) offers a green alternative to conventional vapor compression-based technology. However, extending this novel technology to subzero Celsius temperatures is challenging due to the weak caloric effect (typical adiabatic temperature change Delta T <10 K) and severe functional degradation of existing low-temperature superelastic SMAs. Here, we achieved an ultrastable large elastocaloric effect at low temperatures in Ni51.5Ti48.5 SMA by introducing hyperdense Ti3Ni4 nanoprecipitates with average spacing of only 8.2 nm into the phase-transition (PT) matrix. The formation of hyperdense nanoprecipitates reduces the Ni/Ti ratio of the PT matrix to improve the stress-induced PT latent heat and simultaneously creates a strong coherent strain field to significantly suppress the thermally induced PT. These dual benefits enable a considerable caloric effect with Delta T of 9.4-23.7 K in the temperature window of 213-295 K. Furthermore, these nanoprecipitates and the associated strain field significantly strengthen the PT matrix and improve austenite-martensite compatibility. This effectively suppresses dislocation accumulation and residual martensite formation during cyclic deformation, enabling near-zero functional degradation over 10(5) PT cycles in the entire temperature window mentioned above. Our alloy overcomes the key limitations of existing low-temperature superelastic SMAs, paving the way for subzero Celsius elastocaloric refrigeration.
Wind-induced coastal upwelling plays a significant role in ocean circulations and ecosystems. Although coastal upwelling along eastern boundaries by trade winds is well known, coastal upwelling along western boundaries and its effects in the North-East Pacific Ocean have not been well investigated in previous studies. This study presents surface nutrient supply owing to coastal upwelling along the southeast coast of the Japanese mainland in summer investigated with a coupled physical-biogeochemical model. The model is validated against satellite-based observations (surface temperature and chlorophyll-a), showing good agreement between the model and observations. The summer monsoon (southerly wind) induces coastal upwelling along the coast, leading to rich nutrient conditions near the surface and phytoplankton blooms in the study area. The model results show two hotspots of coastal upwelling on the east sides of the Kii and Boso Peninsulas. Although vertical current transport and turbulent diffusion contribute equally to the surface nitrate supply along the peninsulas, coastal upwelling is identified as the primary contributor to variations in the nutrient supply. In addition to the direct advective surface nutrient supply, coastal upwelling strengthens the vertical nutrient gradient, thereby enhancing vertical diffusive nutrient transport. The Kuroshio Current passes near the upwelling regions, resulting in highly concentrated nutrient/phytoplankton water uptake to the sea surface downstream of the Kuroshio, which results in the nutrient/phytoplankton stream.
The detailed electronic superlattice structure of the Remeika phase compound Nd3Ir4Sn13 was investigated. The material crystallizes in the chiral structure phase (I213). The inequivalent Nd-ion sites in the chiral phase are occupied by different magnetic moments of the 4 f 3 electronic configurations with the total angular moment J = 9/2, which results in two-sublattice antiferromagnetic ordering below TN = 1.41 K. The ordered magnetic moments form circular arrangement within the planes perpendicular to the three-fold rotation axis. The magnetic structure comprises several augmented cluster multipoles including ferri-type arrangement of magnetic toroidal dipoles. The result suggests that Nd3Ir4Sn13 exhibits cross-correlation phenomena.
The photocorrosion of visible-light-responsive photocatalysts is considered detrimental, compromising activity and stability. Although CdS photocorrosion has been extensively reported, most studies focus on performance degradation rather than the underlying facet-dependent mechanisms. Consequently, the origins of facet-selective photocorrosion, the role of solution chemistry (pH, chemical species, and hole-scavenging ability), and the impact of excessive photoetching on photocatalytic activity remain poorly understood. In this study, we demonstrated that the photocorrosion of Pt-loaded wurtzite CdS can be harnessed as a controllable postsynthetic strategy for facet engineering. The photoetching behavior of Pt-loaded CdS photocatalysts was systematically investigated in various aqueous solutions, including lactic acid (LA), acetic acid (AA), sodium lactate (NaLac), and pure water, to elucidate the factors governing facet-selective etching. Distinct etching behaviors were observed depending on solution chemistry. In the LA solution, selective etching predominantly occurred on the Cd-terminated (0001) facet, whereas in AA and pure water, preferential etching of {10-10} and {10-11} side facets was observed. These differences were found to arise from variations in the hole-scavenging ability and coordination chemistry. Insufficient hole scavenging in AA and water led to hole accumulation and corrosion of the side facets, whereas strong chelation of Cd2+ by LA promoted preferential dissolution of the (0001) facet. Light-intensity-dependent experiments revealed that side-facet etching occurs when the carrier generation rate exceeds the hole-consumption capacity of the solution, highlighting the dynamic balance between carrier generation and consumption as a key determinant of etching selectivity. Controlled photoetching of the (0001) facet of Pt-loaded CdS for a short duration generated shallow surface corrugation, resulting in a 2.7-fold enhancement in hydrogen evolution activity. In contrast, excessive etching caused Pt nanoparticle detachment, increased carrier recombination, and reduced activity. These findings establish solution-controlled photoetching as an effective facet-engineering strategy that transforms photocorrosion from a degradation pathway to a design tool for high-performance semiconductor photocatalysts.
The damage initiation and evolution behaviors of ferrite-martensite dual phase (DP), transformation-induced plasticity (TRIP)-aided dual-phase (TDP), quenched and tempered (QT), and TRIP-aided martensitic (TM) steels during tensile deformation were investigated. Voids were initiated at the phase boundaries and inside the martensite in the DP and TDP steels, whereas fine voids were observed at the prior austenite, packet, and block boundaries in the QT and TM steels. In the DP and TDP steels, the size of the voids remarkably increased with the plastic strain, even though the number of voids increased slightly. By contrast, the QT and TM steels exhibited a drastic increase in the number of voids, whereas a slight increase in the size of the voids was observed. The voids in the TM steel hardly extended as the plastic strain increased unlike those in the QT steel. The extent of voids in the DP and TDP steels might be attributed to stress and plastic strain partitioning between the different phases during tensile deformation. In addition, the promotion of void initiation and suppression of void growth might be attributed to the fine and uniform martensite matrix in the QT and TM steels. The suppression of void initiation in the TDP steel and void growth in the TM steel might be attributed to the stress and plastic strain relaxations at the void initiation site and the vicinity of voids owing to the effective martensitic transformation of retained austenite.
